The present invention relates to a motor-driven fuel pump of an in-tank type to be mounted in a fuel tank of an automobile or the like.
A known motor-driven fuel pump of this type includes a cylindrical housing, a pump section fixedly mounted at one end portion of the housing so as to close the one end portion, a motor section mounted in the housing for driving the pump section, and a cover member fixedly mounted at the other end portion of the housing so as to close the other end portion by caulking an end of the housing.
Generally, the end of the housing is caulked to surround a circumferential edge of an outer end surface of the cover member.
In the above known motor-driven fuel pump, it is intended to reduce an operating sound of the pump by increasing a wall thickness of the cover member. However, such an increase in wall thickness of the cover member accompanies an increase in total length of the housing, causing vibration of the housing to generate transmission, conduction and resonance of a motor sound. In contrast, if the wall thickness of the motor cover is reduced, the transmission of the motor sound from the motor section through the motor cover tends to be generated. Thus, a reduction in the operating sound of the pump in the prior art is not fully satisfied. Particularly in the in-tank type motor-driven fuel pump located behind a rear seat of the automobile, the operating sound of the pump is undesirably transmitted to a passenger on the rear seat. Accordingly, it has been demanded to fully reduce the operating sound of the pump.